According to the prior art, and in particular U.S. Pat. No. 6,372,857B1, a device is known for hydrokinetic coupling of two, drive and driven shafts, in particular for a motor vehicle.
In a conventional manner this hydrokinetic coupling device comprises:                a housing which is designed to connect the drive shaft and an impeller wheel in rotation;        a hub which is designed to connect in rotation the driven shaft and a turbine wheel, the turbine wheel being designed to be driven by the impeller wheel by means of circulation of a fluid contained in the housing;        a clutch to lock the coupling of the drive and driven shafts.        
In the case of a motor vehicle automatic transmission, the drive shaft is the output shaft of the vehicle engine, and the driven shaft is connected to means for changing the gear ratio. After starting of the vehicle, the locking clutch, which is also known as the lock-up, makes it possible to avoid undesirable sliding between the wheels of the turbine and the impeller by rendering integral the driven shaft, which is connected to the turbine wheel, and the drive shaft, which is connected to the housing.
The coupling device comprises a damper which is designed to damp the noises and vibrations derived from the engine. This damper comprises first and second damping means which are arranged in parallel by means of a connection disc which is designed to be rendered integral in rotation with one of the drive or driven shafts.
The first damping means comprising resilient units which are distributed circumferentially around the axis of the drive and driven shafts. Each resilient unit extends circumferentially between first support seats which are supported by the connection disc.
The second damping means comprise groups of resilient units, each comprising at least two first resilient units which are arranged in series by means of a first intermediate support element, each group extending circumferentially between second support seats which are supported by the connection disc.
It will be noted that the rigidity of a damper of this type is generally to great to damp the vibrations efficiently in the case of transmission of a high level of torque between the engine and the means for changing the gear ratio of the motor vehicle, and in particular torque greater than 900 Nm (Newton metre).
The object of the invention is in particular to eliminate this disadvantage by providing an efficient damper in the case of transmission of a high level of torque, without modifying the dimensions of the damper.